Carbonato complexes chelate ring opening

Individual steps in chelate ring opening can be followed kinetically during base hydrolysis of [Co en2C03]+, in contrast to acid aquation where only one stage can be monitored kinetically. Thus, while the intermediate formation of a unidentate carbonate complex in acid aquation is a postulate, its formation in alkaline solution is kinetically proven. Further discussion on mechanisms of reactions of carbonato complexes will be found in the kinetic section of a general review on the chemistry of these complexes. ... 

The acid catalyzed aquation of the chelated carbonato complexes involves three steps (i) the initial rapid protonation pre-equilibrium of the exocyclic oxygen, (ii) carbonate ring opening, and (iii) decarboxylation of the resulting bicarbonate complex [see Eq. (30)]. 

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